Platelets will be frozen in the presence of a variety of cryoprotective agents and with varying osmolalities of salt to enable determination of the mechanism of cryoprotection, i.e., whether purely colligative or whether other beneficial or toxic effects are involved. Clinical trials of a platelet freezing procedure using dimethylsulphide will be conducted. The effectiveness of various metabolites in extending liquid storage will be studied. The role of shape change and microtubule disassembly in causing cold-related injury will be studied. The relative effectiveness of platelet storage at 4 degrees and 22 degrees is being evaluated in thrombocytopenic patients.